The present disclosure relates generally to communication networks, and more particularly, to maintaining protocol adjacency state with a forwarding failure.
Bidirectional Forwarding Detection (BFD) is a protocol used to provide rapid failure detection between network devices. BFD detects faults in the bidirectional path between two forwarding engines, including physical interfaces, subinterfaces, data links, and to the extent possible the forwarding engines themselves. The network devices may be configured to support various routing protocols including, for example, IS-IS (Intermediate System-to-Intermediate System), or OSPF (Open Shortest Path First).
For routing protocols whose packets do not share fate with BFD packets (e.g., IS-IS or OSPFv3 supporting IPv4), it is possible that the BFD session fails indicating a real forwarding failure, but the protocol neighbor merely flaps (i.e., goes down due to the BFD down notification but then is restored since the forwarding problem does not impact delivery of the routing protocol packets). This results in a loss of data packets and thus impacts Quality of Service (QoS) and network reliability.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.